Future Feeders Blog

We are building a prototype for a solar passive compost tea aeration unit and are in need of advice on a suitable DC solar power supply.

The Idea : Is a simple and cheap DIY system for farmers to make directly on site and then make their own organic bio active fertilizer from vermicomposted waste. The compost tea can then be fed constantly at low dose and directly into the root zones, via dripline fertigation or foliar application.

The Aim :To make quantities (1000L batch) of bio active compost tea to feed directly into our dripline irrigation system (fertigation) - and excess for sale.This unit is stage II of the vermicompost - worm farm system that we have existing.

The Design : The aim to keep materials cost to a minimum to make the unit functionally affordable for small scale farmers. As such we are aiming for under $1000.

Request : I am requesting some advice, availability and a quote for the most affordable appropriate stand alone solar system. The system will require sufficient stored DC energy to power the pump unit as below or similar for 48H. Battery units will need to be able to maintain continuous operation, however w can assume viability under full sun conditions only.

Additional Details : The brews can be adapted to be more fungal / bacterial dominant and mineral enhanced depending on the requirements of the crop and soil type. Soil Food Web has done great research on this.

There are a number of units like this on the market however this units point of difference is that it is low lech and low cost. Big price tags and technicalities just put farmers off. I am trying to develop an appropriate technology; somethings that just makes sense and is simple and get people using them.These system could easily be adapted for remote communities, developing nations etc

There are 240V systems available, but there is a need for an 'in the field' design that is off grid.

Compost tea applications through fertigition have the potential to have big impacts on soil health, food nutrient density and plant disease resistance. It also give farmers the ability create their own organic inputs and drastically reduce fertilizer costs while cycling nutrients through waste organic matter.

Would really value your input, assistance and support on this project.

How much air do you really need? 140L/m seems a lot, and this pump will require a lot of juice.

Quick estimate: 130W by 24 hours is 3.12 kWh energy required per day. Where i live at -34° the annual average peak sun is 5.5 hours, so you'd want about 650W of solar panels. Then you'd need enough storage to get through the night, 260Ah... Double it for 2 days and divide by 0.8 (because you can't discharge a battery to zero and expect it to perform again), and you need 650 Ah of 12V batteries. Solar panels and batteries come to around $4000, then add wiring, mounting hardware, fuses...

If you find you can cope with 5 to 10L/min, and only while the sun is shining, it could probably be done for under $200.

There are great details to have, Im not so savvy on electrical systems.
Ill see if I can make do with a smaller pump to reduce the system requirements.
Ive sent the design to a couple of local solar system providers.

I might have to experiment with just running it at day time, but I think the biology population with plummet and starve of oxygen if it it not continuously aerated.
Will keep you updated on how this goes through the blog.
Thanks for your interest and help.

Joel

Reply

Karin Six

30/4/2015 06:21:18 am

We are trying to do the same... We have producers (miniature donkeys who also weed & prune) and are going organic! Please let us know what you came up with!

Reply

Joel

30/4/2015 08:32:09 pm

Hi Karin,
keep an eye on this blog and our FB page. if anything eventuates i will post it here.
from what i have found so far, its not very economically sensible to get a small scale solar system to produce the power required on an aerator that will provide enough oxygen, I also looked into a small bilge pump and flow form. still not cheep.
my next option will be to get funding for a small scale solar system to operate our on-site office and resource center and using the inverted power from that system to run a AC pump i think.
I did find a few companies in the US and Canada that do dedicated solar aerators for large ponds, but very pricey.

keep in touch.!

Joel

Reply

Karin Six

1/7/2015 12:53:02 pm

Thank you Joes. We have a 32 gallon trash can and a few solar aerators bought from amazon. We put the compost on a 5 gallon bucket and paint strainer bag. We add molasses too. It aerates for 24 hours and is then strained in muslin. We pour it on our fertilizer tank and it feeds our avocado trees.

Joel

1/7/2015 06:18:19 pm

Hi Karin, great to hear you have had success! keen to hear how your aerators are going? you are happy with them.
What model did you buy, do you have a link.
Would love to hear more and see some pictures of your progress.
please email me joel@futurefeeders.org

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